An Amazon leaffish (Monocirrhus polyacanthus) at Steinhart Aquarium, California Academy of Sciences. (Image Credit: Ben Young Landis/CC-BY)

Another fabulous fish species I got to see up close at the California Academy of Sciences during my visit last Thursday was the Amazon leaffish (Monocirrhus polyacanthus).

Measuring only around 3 inches (8 cm), this small freshwater fish is a native of the Amazon River basin in South America.

It is called the “leaffish” because of its ability to imitate a dead leaf drifting in the water. From its coloration down to its curious habit of floating sideways — using its camouflage and its thin, flat body to sneak up on unsuspecting prey, usually a small fish or shrimp (Catarino and Zuanon 2010).

Amazon leaffish (Monocirrhus polyacanthus) at the Steinhart Aquarium, California Academy of Sciences. (Image Credit: Ben Young Landis/CC-BY)

Once its little transparent pectoral fins maneuver the leaffish into position, its highly extendable, quick-draw jaws do the rest.

The leaffish is a staple of nature documentaries when they have to do a “weird and strange fish” list episode. So let’s jump to the videos!

Animal Planet, where we see the crazy jaws in action:

National Geographic, which offer a close-up view of the fully extended, vacuum-like jaws:

And look — a video from the California Academy of Sciences on leaffish! Here, the Steinhart Aquarium staff are feeding their leaffish collection with what appears to be about a bajillion little brine shrimp.

I can only imagine what was going on in those tiny leaffish brains at the sight of that massive brine shrimp swarm — it’s probably what I would feel if the heavens opened up and started raining In-N-Out hamburgers…

Here is some pretty cool footage of a leaffish drifting along in a stream in Venezuela:

And finally, our Random Fish Video Set to Crazy Soundtracks, this one set to the James Bond theme and “Kashmir” by Led Zeppelin:

Monocirrhus polyacanthus Heckel, 1840
Amazon Leaffish (click for names in other languages)

Class Actinopterygii (Ray-finned Fishes)
Order Perciformes (Perch-like Fishes)
Family Polycentridae (Leaffishes)

FishBase Page: http://www.fishbase.org/summary/Monocirrhus-polyacanthus.html

Citations

Catarino, MF, J Zuanon. 2010. Feeding ecology of the leaf fish Monocirrhus polyacanthus (Perciformes: Polycentridae) in a terra firme stream in the Brazilian Amazon. Neotropical Ichthyology 8(1): 183-186. doi: 10.1590/S1679-62252010000100022

— Ben Young Landis